Getting null for SkeletonAnimation.state

Aggressor

Howdy

So I have an awake call like this:

 protected SkeletonData _skeletonData;
 protected AnimationStateData _animationStateData;
protected SkeletonAnimation _animator;
protected Spine.AnimationState _baseState;

// Use this for initialization
public void Awake () 
 {
   _animator = GetComponentInChildren<SkeletonAnimation>();
   _baseState = _animator.state;
     Debug.Log("Base animator is " + _animator); //NO NULL
     Debug.Log("Base animator state is " + _animator.state);//ALWAYS NULL
     Debug.Log("Base base state is " + _baseState);
}

Basically I just spawn 7 units and these units have this script on them in their awake call. However _animator.state is always null.

Any idea what I am doing wrong?

(Also note the prefab that this script is attached to has its default spine animation set to idle)

Mitch

use Start

Aggressor

Yea same issue 😛

Mitch

Check for it on Update and see if it stays null. If its not null after the first frame, its a problem with your script execution order. If not, its not a valid skeleton. state is initialized by SkeletonAnimation on Start.

Pharan

SkeletonAnimation subclasses/extends SkeletonRenderer.
Let me walk you through the stack:

SkeletonAnimation overrides SkeletonRenderer.Reset

SkeletonRenderer.Awake calls Reset
- SkeletonAnimation.Reset calls SkeletonRenderer.Reset.
- SkeletonRenderer.Reset generates the necessary data structures and tries to instantiate its Spine.Skeleton.
- if SkeletonRenderer.Reset resulted in a valid skeleton (valid == true) then SkeletonAnimation.Reset instantiates its Spine.AnimationState

this Spine.AnimationState is what's stored as SkeletonAnimation.state
Under normal circumstances, all of this will be done when Awake returns.
Start is where it's safe to pick up the state reference.

If you spawn a prefab and both the SkeletonAnimation component and your picking-up script are on the same prefab, it should still work correctly if you pick up the reference on Start. I've done this dozens of times without problems.

Unity trivia that might be relevant:
Awake is called even if your MonoBehaviour is disabled.
But Awake isn't called if your GameObject is disabled. If your prefab has disabled GameObjects with SkeletonAnimations on them and that's what you're trying to get, these results may be expected. If that's the case, you'll have to call Reset yourself.

SkeletonRenderer (back when it was SkeletonComponent) used to have an Initialize() method that was safe to call multiple times precisely for cases like this (and also in places where it makes perfect sense to pick up AnimationState on Awake) but it got removed.

Aggressor

Cool Im going to dig into this now. Thanks!

(P.S. its not null after the first frame for sure)

It seems calling the animation on the same frame that I create the unit causes the issue. Very odd..

 var unit= Instantiate(Resources.Load("Prefabs/unit", typeof(GameObject))) as GameObject;
unit.SendMessage("PlayIdle"); //causes error

However if I do this

 var unit= Instantiate(Resources.Load("Prefabs/unit", typeof(GameObject))) as GameObject;
StartCoroutine("playIdle");

 IEnumerator playIdle()
    {
        yield return new WaitForSeconds(1);
        foreach(GameObject unit in units)
        {
            unit.SendMessage("PlayIdle");
        }
    }

I get no error.

Perhaps theres something funky going on under the hood.

Also Pharan I checked for any disabled scripts, everything is a go. I have a prefab premade on the scene and it DOESNT give the error. Its only the new units I spawn at runtime that give the error (and they are carbon copies of the one already in the scene which doesnt generate the error).

Pharan

Have you tried calling Reset on them before doing anything with the SkeletonAnimation scripts' AnimationState?

Aggressor

I tried this

public void Start () 
    {
      _animator = GetComponentInChildren<SkeletonAnimation>();
      _animator.Reset()
      _baseState = _animator.state;
}

No go

Also tried this

//Instantiate code
 unit.GetComponent<UnitAnimator>().reset();

 public void reset()
    {
         //animator was set in Start()
        _animator.Reset();
    }

Still get the error.

the SkeletonAnimation object (my _animator) is NOT null in the start call, but the _animator.state is. Very curious 🙂

Mitch

Oh you're loading from Resources.

I remember whats going on here.

You actually need to load the TXT files using Resources.Load separately before you try and instantiate the Prefab of your unit. I know. Its stupid. Try it.

Resources.Load("mySkeletonJson.json") and "mySkeletonAtlas.atlas.txt" so on. Load those first, you dont even need to store them anywhere - just get Resources to load them.

Pharan

lol. nice catch. totally didn't notice Resources.Load

Aggressor

Interesting.

Ok well for the time being Im just going to have the prefab be idling and not call the play idle the frame I summon it.

But very good catch, I may need this in the future if I change my mind how I want to do the spawner.

Thank you Mitch!

Mitch

Just for reference, this applies to AssetBundles too. You need to implicitly call Load on the TextAssets if you want to use them in the same frame that you instantiate the SkeletonAnimation. I don't remember what version I proved that on but there ya go.